KEF 104/2 - The speaker gods have spoken

Discussion in 'Speakers' started by baco99, Apr 9, 2013.

  1. slimecity

    slimecity Super Member

    Messages:
    2,691
    Location:
    New Zealand
    Did my ferrofluid - yes it wasnt too painful. What was there wasnt dried up however it had become extremely gluggy and had collected on the VC's in dried globs in places. Im glad I did this.

    I have also done the donuts but havent been able to audition yet as Im currently repainting my speakers with the Duratex PA speaker paint (the stain and veneer was pretty much shot).
     

     

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  2. BMW C1

    BMW C1 New Member

    Messages:
    2
    Hi baco99 thanks for your response, I prefered the Q7s with my turntable but found the 104/2 perfect for my home cinema setup.
    I moved house recently so everything was dismantled and put into storage.
    Now my two sons are insisting we set up a boys room.
    I have a set of B&W SCM8 THX surround speakers and a Linn AV5120 Centre speaker.
    If I refurb the 104/2s they will be perfect for the front L/R without the need for a subwoofer.
    I've mounted the B&Ws and I'm now in the process of finding decent speaker cable.
     
  3. WE6C

    WE6C Well-Known Member

    Messages:
    510
    Location:
    Colfax, Northern California
    I am not a wood worker (can build shelves for garages etc) but I never knew you could paint the speakers. Can they be made to end up with a nice wood color using paint?
     
  4. slimecity

    slimecity Super Member

    Messages:
    2,691
    Location:
    New Zealand
    Probably but I have gone in the opposite direction - Duratex is a durable and grunty industrial black protective coat for PA speakers - I went that route instead of trying to replicate a wood look. It wont be for everyone but it suits me as these are such industrial looking speakers anyway.

    The KEF 104/2 cabinets are stained and then coated with a clear poly coat. So the usual rules apply - sand back the poly coat to de-gloss and then you should be good to go. I also applied a sealer before top-coating to be safe.

    It really was a last resort in my case as I buggered up the staining. However I think I will be happier with this finish in the end.
     
  5. WE6C

    WE6C Well-Known Member

    Messages:
    510
    Location:
    Colfax, Northern California
    Slimecity, Thanks for your answer. Sorry it took so long for me to respond (no internet for a week).
    Bob
     
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  6. bcurtin

    bcurtin New Member

    Messages:
    19
    Picked up some KEF 104s on Craigslist as an upgrade to some B&Ws and first foray into speaker restoration. They sounded great before taking them apart, and I had some questions about what to be concerned about.

    The foam on all four woofers was in really bad shape (crumbling), so I pulled them out and cleaned off the old foam residue and adhesive with iso and an xacto blade. What’s the best way to check for coil rubbing? The outer diaphragm is butyl and there’s rubbing if I press on the cone, and some vibration when I play a <100 Hz test tone from my phone but it disappears when I lightly push on the cone. The gap also seems non-uniform when press down, with one side getting closer than the other. It’s not clear how I could slip something into the gap to clear debris or adjust to give the tighter side more space, if this is even necessary.

    This seems concerning but perhaps I’m not testing the right way. I’d like to diagnose and do what I can before glueing the new foam dust covers on.
     

     

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  7. tubed

    tubed Lunatic Member

    Messages:
    14,797
    Location:
    Aztlan
    Manipulating the woofers by hand isn't a good test.
    The test tone result is disconcerting, perhaps there is debris causing this and a vacuum nozzle could remove the v/c rub.
    I'd resolve this issue before replacing the dust covers.
     
  8. baco99

    baco99 AK Subscriber Subscriber

    Messages:
    9,003
    Location:
    Lawrence, MA

    You most likely have left over foam bits inside the voice coil. The foam gets sticky. If the gap is big enough to fit a business card in there, out a few drops of alcohol in the gap (don't soak it), let the alcohol dry a little, then scrape with the business card. You should see black gunk come out. If it comes out clean, you may have a blown coil.
     
  9. WE6C

    WE6C Well-Known Member

    Messages:
    510
    Location:
    Colfax, Northern California
    I suggest you watch some youtube videos on refoaming etc. You will see how shims are used to align the cone as you glue in the center donut. As others have said, clean it all as best you can. You may be ok.
     
  10. bcurtin

    bcurtin New Member

    Messages:
    19
    Thanks for all the advice! I took some of the spacers that came with my re-foam kit and slid them around the voice coil gap, and so far the rubbing seems to have mostly gone away. There was some residue that came out and I'll follow up with some isopropanol before gluing the new dust caps on.

    WE6C - Are you referring to the shims used to align the voice coil for the outer foam replacement? My drivers have butyl surrounds and I'm not sure how I'd use a spacer with the dust caps since this area will be sealed once I put them on.
     
  11. WE6C

    WE6C Well-Known Member

    Messages:
    510
    Location:
    Colfax, Northern California
    No. I was describing exactly what you mentioned in your first paragraph above. I called them shims, you called them spacers, but it gets the cone properly aligned with the voice coil etc.

    Looks like you got it!
     

     

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  12. bcurtin

    bcurtin New Member

    Messages:
    19
    Hit a snag while pulling out the tweeters to remove/replace ferrofluid - one tweeter reads open which was likely from me removing the adhesive and indenting an area around the magnetic coil. The first tweeter came out well, so I'm in the market for a replacement pair (MT-1191) or single T33/SP-1191.

    Is there a recommendation for which path would be better? There doesn't seem to be any spare T33s listed on Ebay currently or on other used audio sites.
     
  13. WE6C

    WE6C Well-Known Member

    Messages:
    510
    Location:
    Colfax, Northern California
    Don't give up yet. Find where the coil became open circuit. It may be in an accessible location such as behind the black soft foam. If so get one strand of some stranded wire and solder it in over the break. You have absolutely nothing to loose. I had one go open circuit in that location for an unknown reason and fixed it as I just described. Don't give up yet.
     
  14. bcurtin

    bcurtin New Member

    Messages:
    19
    Thanks for the advice - I took a look and it appears to be a break where the wire from a terminal meets the main coil. I tried to beep out the open but it's pretty tightly wound there so my tools might not cut it.
     
  15. bcurtin

    bcurtin New Member

    Messages:
    19
    That was some challenging repair work, but I can now measure low resistance across the tweeter and did a tone check - so far so good! I ended up having to solder wire to bridge the wire from the terminal next to the voice coil and the detached voice coil wire. Thank you for the words of encouragement!
     
  16. WE6C

    WE6C Well-Known Member

    Messages:
    510
    Location:
    Colfax, Northern California
    Great! Time to celebrate! Anxious to hear your thoughts after getting them all back together.

    Bob
     

     

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  17. bcurtin

    bcurtin New Member

    Messages:
    19
    Got them both reassembled after stripping and oiling the cabinets - wow! The depth of these speakers compared to my B&W DM601s are outstanding, and I'm happy that I put in the effort to restore them.

    Not sure whether replacing the FF made an audible difference, but I don't get the impression that highs are recessed or less present as others have described and think voices sound fantastic. It had also been a while since I listened to them so it's impossible to make a proper comparison. No audible difference between tweeters either, so my patch job came out OK :)

    I noticed one of the mid-range drivers had bad distortion after assembling the cabinets, which disappeared when they were on their side. The voice coil might have some debris or gotten distorted when cleaning/repairing, so I tried pushing it in with even pressure and this seems to have fixed it for now. Mids are very clear and detailed, so some debris that I was able to dislodge and not an intermittent issue.

    One speaker stripped, the other ready:
    [​IMG]

    Both speakers stripped and ready for oil:
    [​IMG]

    Reassembled after Danish Oil, re-foaming the woofers, and replacing FF in the tweeters:
    [​IMG]
     
    Last edited: Jun 21, 2018
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  18. WE6C

    WE6C Well-Known Member

    Messages:
    510
    Location:
    Colfax, Northern California
    They look great. Good job!
     
  19. baco99

    baco99 AK Subscriber Subscriber

    Messages:
    9,003
    Location:
    Lawrence, MA
    @bcurtin - Definitely possible that a piece of foam got lodged in the midrange pod voice coil. The midrange is integrated into the pod itself. There is no basket like a traditional driver. The cone suspension is attached to foam and the magnet is epoxied to the rear of the chamber.

    "Never before seen photos inside the midrange pod."

    [​IMG]

    [​IMG]

    (Photo credits to Scott Parkhurst)
     
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